I put the following report together to query various pieces of IO data and highlight whether those metrics are above certain thresholds, which I've defined as parameters. In a perfect world, you would like to see <20ms for reads and <4ms for writes, but in many cases that's not a reality. We're still working with SANs that have older, slower drives or whatever the case may be. At any rate, you can adjust the read/write goals and the report will highlight the metrics accordingly.
Preview of report: